/*
 * Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xpath.internal;

import com.sun.org.apache.xalan.internal.res.XSLMessages;
import com.sun.org.apache.xml.internal.utils.DOM2Helper;
import com.sun.org.apache.xpath.internal.axes.ContextNodeList;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;

import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.NodeIterator;


/**
 * <p>The NodeSet class can act as either a NodeVector,
 * NodeList, or NodeIterator.  However, in order for it to
 * act as a NodeVector or NodeList, it's required that
 * setShouldCacheNodes(true) be called before the first
 * nextNode() is called, in order that nodes can be added
 * as they are fetched.  Derived classes that implement iterators
 * must override runTo(int index), in order that they may
 * run the iteration to the given index. </p>
 *
 * <p>Note that we directly implement the DOM's NodeIterator
 * interface. We do not emulate all the behavior of the
 * standard NodeIterator. In particular, we do not guarantee
 * to present a "live view" of the document ... but in XSLT,
 * the source document should never be mutated, so this should
 * never be an issue.</p>
 *
 * <p>Thought: Should NodeSet really implement NodeList and NodeIterator,
 * or should there be specific subclasses of it which do so? The
 * advantage of doing it all here is that all NodeSets will respond
 * to the same calls; the disadvantage is that some of them may return
 * less-than-enlightening results when you do so.</p>
 *
 * @xsl.usage advanced
 */
public class NodeSet
        implements NodeList, NodeIterator, Cloneable, ContextNodeList {

    /**
     * Create an empty nodelist.
     */
    public NodeSet() {
        m_blocksize = 32;
        m_mapSize = 0;
    }

    /**
     * Create an empty, using the given block size.
     *
     * @param blocksize Size of blocks to allocate
     */
    public NodeSet(int blocksize) {
        m_blocksize = blocksize;
        m_mapSize = 0;
    }

    /**
     * Create a NodeSet, and copy the members of the
     * given nodelist into it.
     *
     * @param nodelist List of Nodes to be made members of the new set.
     */
    public NodeSet(NodeList nodelist) {

        this(32);

        addNodes(nodelist);
    }

    /**
     * Create a NodeSet, and copy the members of the
     * given NodeSet into it.
     *
     * @param nodelist Set of Nodes to be made members of the new set.
     */
    public NodeSet(NodeSet nodelist) {

        this(32);

        addNodes((NodeIterator) nodelist);
    }

    /**
     * Create a NodeSet, and copy the members of the
     * given NodeIterator into it.
     *
     * @param ni Iterator which yields Nodes to be made members of the new set.
     */
    public NodeSet(NodeIterator ni) {

        this(32);

        addNodes(ni);
    }

    /**
     * Create a NodeSet which contains the given Node.
     *
     * @param node Single node to be added to the new set.
     */
    public NodeSet(Node node) {

        this(32);

        addNode(node);
    }

    /**
     * @return The root node of the Iterator, as specified when it was created.
     * For non-Iterator NodeSets, this will be null.
     */
    public Node getRoot() {
        return null;
    }

    /**
     * Get a cloned Iterator, and reset its state to the beginning of the
     * iteration.
     *
     * @return a new NodeSet of the same type, having the same state...
     * except that the reset() operation has been called.
     * @throws CloneNotSupportedException if this subclass of NodeSet
     *                                    does not support the clone() operation.
     */
    public NodeIterator cloneWithReset() throws CloneNotSupportedException {

        NodeSet clone = (NodeSet) clone();

        clone.reset();

        return clone;
    }

    /**
     * Reset the iterator. May have no effect on non-iterator Nodesets.
     */
    public void reset() {
        m_next = 0;
    }

    /**
     * This attribute determines which node types are presented via the
     * iterator. The available set of constants is defined in the
     * <code>NodeFilter</code> interface. For NodeSets, the mask has been
     * hardcoded to show all nodes except EntityReference nodes, which have
     * no equivalent in the XPath data model.
     *
     * @return integer used as a bit-array, containing flags defined in
     * the DOM's NodeFilter class. The value will be
     * <code>SHOW_ALL & ~SHOW_ENTITY_REFERENCE</code>, meaning that
     * only entity references are suppressed.
     */
    public int getWhatToShow() {
        return NodeFilter.SHOW_ALL & ~NodeFilter.SHOW_ENTITY_REFERENCE;
    }

    /**
     * The filter object used to screen nodes. Filters are applied to
     * further reduce (and restructure) the NodeIterator's view of the
     * document. In our case, we will be using hardcoded filters built
     * into our iterators... but getFilter() is part of the DOM's
     * NodeIterator interface, so we have to support it.
     *
     * @return null, which is slightly misleading. True, there is no
     * user-written filter object, but in fact we are doing some very
     * sophisticated custom filtering. A DOM purist might suggest
     * returning a placeholder object just to indicate that this is
     * not going to return all nodes selected by whatToShow.
     */
    public NodeFilter getFilter() {
        return null;
    }

    /**
     * The value of this flag determines whether the children of entity
     * reference nodes are visible to the iterator. If false, they will be
     * skipped over.
     * <br> To produce a view of the document that has entity references
     * expanded and does not expose the entity reference node itself, use the
     * whatToShow flags to hide the entity reference node and set
     * expandEntityReferences to true when creating the iterator. To produce
     * a view of the document that has entity reference nodes but no entity
     * expansion, use the whatToShow flags to show the entity reference node
     * and set expandEntityReferences to false.
     *
     * @return true for all iterators based on NodeSet, meaning that the
     * contents of EntityRefrence nodes may be returned (though whatToShow
     * says that the EntityReferences themselves are not shown.)
     */
    public boolean getExpandEntityReferences() {
        return true;
    }

    /**
     * Returns the next node in the set and advances the position of the
     * iterator in the set. After a NodeIterator is created, the first call
     * to nextNode() returns the first node in the set.
     *
     * @return The next <code>Node</code> in the set being iterated over, or
     * <code>null</code> if there are no more members in that set.
     * @throws DOMException INVALID_STATE_ERR: Raised if this method is called after the
     *                      <code>detach</code> method was invoked.
     */
    public Node nextNode() throws DOMException {

        if ((m_next) < this.size()) {
            Node next = this.elementAt(m_next);

            m_next++;

            return next;
        } else
            return null;
    }

    /**
     * Returns the previous node in the set and moves the position of the
     * iterator backwards in the set.
     *
     * @return The previous <code>Node</code> in the set being iterated over,
     * or<code>null</code> if there are no more members in that set.
     * @throws DOMException     INVALID_STATE_ERR: Raised if this method is called after the
     *                          <code>detach</code> method was invoked.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a cached type, and hence doesn't know what the previous node was.
     */
    public Node previousNode() throws DOMException {

        if (!m_cacheNodes)
            throw new RuntimeException(
                    XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_CANNOT_ITERATE, null)); //"This NodeSet can not iterate to a previous node!");

        if ((m_next - 1) > 0) {
            m_next--;

            return this.elementAt(m_next);
        } else
            return null;
    }

    /**
     * Detaches the iterator from the set which it iterated over, releasing
     * any computational resources and placing the iterator in the INVALID
     * state. After<code>detach</code> has been invoked, calls to
     * <code>nextNode</code> or<code>previousNode</code> will raise the
     * exception INVALID_STATE_ERR.
     * <p>
     * This operation is a no-op in NodeSet, and will not cause
     * INVALID_STATE_ERR to be raised by later operations.
     * </p>
     */
    public void detach() {
    }

    /**
     * Tells if this NodeSet is "fresh", in other words, if
     * the first nextNode() that is called will return the
     * first node in the set.
     *
     * @return true if nextNode() would return the first node in the set,
     * false if it would return a later one.
     */
    public boolean isFresh() {
        return (m_next == 0);
    }

    /**
     * If an index is requested, NodeSet will call this method
     * to run the iterator to the index.  By default this sets
     * m_next to the index.  If the index argument is -1, this
     * signals that the iterator should be run to the end.
     *
     * @param index Position to advance (or retreat) to, with
     *              0 requesting the reset ("fresh") position and -1 (or indeed
     *              any out-of-bounds value) requesting the final position.
     * @throws RuntimeException thrown if this NodeSet is not
     *                          one of the types which supports indexing/counting.
     */
    public void runTo(int index) {

        if (!m_cacheNodes)
            throw new RuntimeException(
                    XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_CANNOT_INDEX, null)); //"This NodeSet can not do indexing or counting functions!");

        if ((index >= 0) && (m_next < m_firstFree))
            m_next = index;
        else
            m_next = m_firstFree - 1;
    }

    /**
     * Returns the <code>index</code>th item in the collection. If
     * <code>index</code> is greater than or equal to the number of nodes in
     * the list, this returns <code>null</code>.
     * <p>
     * TODO: What happens if index is out of range?
     *
     * @param index Index into the collection.
     * @return The node at the <code>index</code>th position in the
     * <code>NodeList</code>, or <code>null</code> if that is not a valid
     * index.
     */
    public Node item(int index) {

        runTo(index);

        return (Node) this.elementAt(index);
    }

    /**
     * The number of nodes in the list. The range of valid child node indices is
     * 0 to <code>length-1</code> inclusive. Note that this operation requires
     * finding all the matching nodes, which may defeat attempts to defer
     * that work.
     *
     * @return integer indicating how many nodes are represented by this list.
     */
    public int getLength() {

        runTo(-1);

        return this.size();
    }

    /**
     * Add a node to the NodeSet. Not all types of NodeSets support this
     * operation
     *
     * @param n Node to be added
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNode(Node n) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        this.addElement(n);
    }

    /**
     * Insert a node at a given position.
     *
     * @param n   Node to be added
     * @param pos Offset at which the node is to be inserted,
     *            with 0 being the first position.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void insertNode(Node n, int pos) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        insertElementAt(n, pos);
    }

    /**
     * Remove a node.
     *
     * @param n Node to be added
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void removeNode(Node n) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        this.removeElement(n);
    }

    /**
     * Copy NodeList members into this nodelist, adding in
     * document order.  If a node is null, don't add it.
     *
     * @param nodelist List of nodes which should now be referenced by
     *                 this NodeSet.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNodes(NodeList nodelist) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if (null != nodelist)  // defensive to fix a bug that Sanjiva reported.
        {
            int nChildren = nodelist.getLength();

            for (int i = 0; i < nChildren; i++) {
                Node obj = nodelist.item(i);

                if (null != obj) {
                    addElement(obj);
                }
            }
        }

        // checkDups();
    }

    /**
     * <p>Copy NodeList members into this nodelist, adding in
     * document order.  Only genuine node references will be copied;
     * nulls appearing in the source NodeSet will
     * not be added to this one. </p>
     *
     * <p> In case you're wondering why this function is needed: NodeSet
     * implements both NodeIterator and NodeList. If this method isn't
     * provided, Java can't decide which of those to use when addNodes()
     * is invoked. Providing the more-explicit match avoids that
     * ambiguity.)</p>
     *
     * @param ns NodeSet whose members should be merged into this NodeSet.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNodes(NodeSet ns) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        addNodes((NodeIterator) ns);
    }

    /**
     * Copy NodeList members into this nodelist, adding in
     * document order.  Null references are not added.
     *
     * @param iterator NodeIterator which yields the nodes to be added.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNodes(NodeIterator iterator) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if (null != iterator)  // defensive to fix a bug that Sanjiva reported.
        {
            Node obj;

            while (null != (obj = iterator.nextNode())) {
                addElement(obj);
            }
        }

        // checkDups();
    }

    /**
     * Copy NodeList members into this nodelist, adding in
     * document order.  If a node is null, don't add it.
     *
     * @param nodelist List of nodes to be added
     * @param support  The XPath runtime context.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNodesInDocOrder(NodeList nodelist, XPathContext support) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        int nChildren = nodelist.getLength();

        for (int i = 0; i < nChildren; i++) {
            Node node = nodelist.item(i);

            if (null != node) {
                addNodeInDocOrder(node, support);
            }
        }
    }

    /**
     * Copy NodeList members into this nodelist, adding in
     * document order.  If a node is null, don't add it.
     *
     * @param iterator NodeIterator which yields the nodes to be added.
     * @param support  The XPath runtime context.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public void addNodesInDocOrder(NodeIterator iterator, XPathContext support) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        Node node;

        while (null != (node = iterator.nextNode())) {
            addNodeInDocOrder(node, support);
        }
    }

    /**
     * Add the node list to this node set in document order.
     *
     * @param start     index.
     * @param end       index.
     * @param testIndex index.
     * @param nodelist  The nodelist to add.
     * @param support   The XPath runtime context.
     * @return false always.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    private boolean addNodesInDocOrder(int start, int end, int testIndex,
                                       NodeList nodelist, XPathContext support) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        boolean foundit = false;
        int i;
        Node node = nodelist.item(testIndex);

        for (i = end; i >= start; i--) {
            Node child = (Node) elementAt(i);

            if (child == node) {
                i = -2;  // Duplicate, suppress insert

                break;
            }

            if (!DOM2Helper.isNodeAfter(node, child)) {
                insertElementAt(node, i + 1);

                testIndex--;

                if (testIndex > 0) {
                    boolean foundPrev = addNodesInDocOrder(0, i, testIndex, nodelist,
                            support);

                    if (!foundPrev) {
                        addNodesInDocOrder(i, size() - 1, testIndex, nodelist, support);
                    }
                }

                break;
            }
        }

        if (i == -1) {
            insertElementAt(node, 0);
        }

        return foundit;
    }

    /**
     * Add the node into a vector of nodes where it should occur in
     * document order.
     *
     * @param node    The node to be added.
     * @param test    true if we should test for doc order
     * @param support The XPath runtime context.
     * @return insertIndex.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public int addNodeInDocOrder(Node node, boolean test, XPathContext support) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        int insertIndex = -1;

        if (test) {

            // This needs to do a binary search, but a binary search
            // is somewhat tough because the sequence test involves
            // two nodes.
            int size = size(), i;

            for (i = size - 1; i >= 0; i--) {
                Node child = (Node) elementAt(i);

                if (child == node) {
                    i = -2;  // Duplicate, suppress insert

                    break;
                }

                if (!DOM2Helper.isNodeAfter(node, child)) {
                    break;
                }
            }

            if (i != -2) {
                insertIndex = i + 1;

                insertElementAt(node, insertIndex);
            }
        } else {
            insertIndex = this.size();

            boolean foundit = false;

            for (int i = 0; i < insertIndex; i++) {
                if (this.item(i).equals(node)) {
                    foundit = true;

                    break;
                }
            }

            if (!foundit)
                addElement(node);
        }

        // checkDups();
        return insertIndex;
    }  // end addNodeInDocOrder(Vector v, Object obj)

    /**
     * Add the node into a vector of nodes where it should occur in
     * document order.
     *
     * @param node    The node to be added.
     * @param support The XPath runtime context.
     * @return The index where it was inserted.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a mutable type.
     */
    public int addNodeInDocOrder(Node node, XPathContext support) {

        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        return addNodeInDocOrder(node, true, support);
    }  // end addNodeInDocOrder(Vector v, Object obj)


    /**
     * If this node is being used as an iterator, the next index that nextNode()
     * will return.
     */
    transient protected int m_next = 0;

    /**
     * Get the current position, which is one less than
     * the next nextNode() call will retrieve.  i.e. if
     * you call getCurrentPos() and the return is 0, the next
     * fetch will take place at index 1.
     *
     * @return The the current position index.
     */
    public int getCurrentPos() {
        return m_next;
    }

    /**
     * Set the current position in the node set.
     *
     * @param i Must be a valid index.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a cached type, and thus doesn't permit indexed access.
     */
    public void setCurrentPos(int i) {

        if (!m_cacheNodes)
            throw new RuntimeException(
                    XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_CANNOT_INDEX, null)); //"This NodeSet can not do indexing or counting functions!");

        m_next = i;
    }

    /**
     * Return the last fetched node.  Needed to support the UnionPathIterator.
     *
     * @return the last fetched node.
     * @throws RuntimeException thrown if this NodeSet is not of
     *                          a cached type, and thus doesn't permit indexed access.
     */
    public Node getCurrentNode() {

        if (!m_cacheNodes)
            throw new RuntimeException(
                    XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_CANNOT_INDEX, null)); //"This NodeSet can not do indexing or counting functions!");

        int saved = m_next;
        Node n = (m_next < m_firstFree) ? elementAt(m_next) : null;
        m_next = saved; // HACK: I think this is a bit of a hack.  -sb
        return n;
    }

    /**
     * True if this list can be mutated.
     */
    transient protected boolean m_mutable = true;

    /**
     * True if this list is cached.
     *
     * @serial
     */
    transient protected boolean m_cacheNodes = true;

    /**
     * Get whether or not this is a cached node set.
     *
     * @return True if this list is cached.
     */
    public boolean getShouldCacheNodes() {
        return m_cacheNodes;
    }

    /**
     * If setShouldCacheNodes(true) is called, then nodes will
     * be cached.  They are not cached by default. This switch must
     * be set before the first call to nextNode is made, to ensure
     * that all nodes are cached.
     *
     * @param b true if this node set should be cached.
     * @throws RuntimeException thrown if an attempt is made to
     *                          request caching after we've already begun stepping through the
     *                          nodes in this set.
     */
    public void setShouldCacheNodes(boolean b) {

        if (!isFresh())
            throw new RuntimeException(
                    XSLMessages.createXPATHMessage(XPATHErrorResources.ER_CANNOT_CALL_SETSHOULDCACHENODE, null)); //"Can not call setShouldCacheNodes after nextNode has been called!");

        m_cacheNodes = b;
        m_mutable = true;
    }


    transient private int m_last = 0;

    public int getLast() {
        return m_last;
    }

    public void setLast(int last) {
        m_last = last;
    }

    /**
     * Size of blocks to allocate.
     *
     * @serial
     */
    private int m_blocksize;

    /**
     * Array of nodes this points to.
     *
     * @serial
     */
    Node m_map[];

    /**
     * Number of nodes in this NodeVector.
     *
     * @serial
     */
    protected int m_firstFree = 0;

    /**
     * Size of the array this points to.
     *
     * @serial
     */
    private int m_mapSize;  // lazy initialization

    /**
     * Get a cloned LocPathIterator.
     *
     * @return A clone of this
     * @throws CloneNotSupportedException
     */
    public Object clone() throws CloneNotSupportedException {

        NodeSet clone = (NodeSet) super.clone();

        if ((null != this.m_map) && (this.m_map == clone.m_map)) {
            clone.m_map = new Node[this.m_map.length];

            System.arraycopy(this.m_map, 0, clone.m_map, 0, this.m_map.length);
        }

        return clone;
    }

    /**
     * Get the length of the list.
     *
     * @return Number of nodes in this NodeVector
     */
    public int size() {
        return m_firstFree;
    }

    /**
     * Append a Node onto the vector.
     *
     * @param value Node to add to the vector
     */
    public void addElement(Node value) {
        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if ((m_firstFree + 1) >= m_mapSize) {
            if (null == m_map) {
                m_map = new Node[m_blocksize];
                m_mapSize = m_blocksize;
            } else {
                m_mapSize += m_blocksize;

                Node newMap[] = new Node[m_mapSize];

                System.arraycopy(m_map, 0, newMap, 0, m_firstFree + 1);

                m_map = newMap;
            }
        }

        m_map[m_firstFree] = value;

        m_firstFree++;
    }

    /**
     * Append a Node onto the vector.
     *
     * @param value Node to add to the vector
     */
    public final void push(Node value) {

        int ff = m_firstFree;

        if ((ff + 1) >= m_mapSize) {
            if (null == m_map) {
                m_map = new Node[m_blocksize];
                m_mapSize = m_blocksize;
            } else {
                m_mapSize += m_blocksize;

                Node newMap[] = new Node[m_mapSize];

                System.arraycopy(m_map, 0, newMap, 0, ff + 1);

                m_map = newMap;
            }
        }

        m_map[ff] = value;

        ff++;

        m_firstFree = ff;
    }

    /**
     * Pop a node from the tail of the vector and return the result.
     *
     * @return the node at the tail of the vector
     */
    public final Node pop() {

        m_firstFree--;

        Node n = m_map[m_firstFree];

        m_map[m_firstFree] = null;

        return n;
    }

    /**
     * Pop a node from the tail of the vector and return the
     * top of the stack after the pop.
     *
     * @return The top of the stack after it's been popped
     */
    public final Node popAndTop() {

        m_firstFree--;

        m_map[m_firstFree] = null;

        return (m_firstFree == 0) ? null : m_map[m_firstFree - 1];
    }

    /**
     * Pop a node from the tail of the vector.
     */
    public final void popQuick() {

        m_firstFree--;

        m_map[m_firstFree] = null;
    }

    /**
     * Return the node at the top of the stack without popping the stack.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @return Node at the top of the stack or null if stack is empty.
     */
    public final Node peepOrNull() {
        return ((null != m_map) && (m_firstFree > 0))
                ? m_map[m_firstFree - 1] : null;
    }

    /**
     * Push a pair of nodes into the stack.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @param v1 First node to add to vector
     * @param v2 Second node to add to vector
     */
    public final void pushPair(Node v1, Node v2) {

        if (null == m_map) {
            m_map = new Node[m_blocksize];
            m_mapSize = m_blocksize;
        } else {
            if ((m_firstFree + 2) >= m_mapSize) {
                m_mapSize += m_blocksize;

                Node newMap[] = new Node[m_mapSize];

                System.arraycopy(m_map, 0, newMap, 0, m_firstFree);

                m_map = newMap;
            }
        }

        m_map[m_firstFree] = v1;
        m_map[m_firstFree + 1] = v2;
        m_firstFree += 2;
    }

    /**
     * Pop a pair of nodes from the tail of the stack.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     */
    public final void popPair() {

        m_firstFree -= 2;
        m_map[m_firstFree] = null;
        m_map[m_firstFree + 1] = null;
    }

    /**
     * Set the tail of the stack to the given node.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @param n Node to set at the tail of vector
     */
    public final void setTail(Node n) {
        m_map[m_firstFree - 1] = n;
    }

    /**
     * Set the given node one position from the tail.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @param n Node to set
     */
    public final void setTailSub1(Node n) {
        m_map[m_firstFree - 2] = n;
    }

    /**
     * Return the node at the tail of the vector without popping
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @return Node at the tail of the vector
     */
    public final Node peepTail() {
        return m_map[m_firstFree - 1];
    }

    /**
     * Return the node one position from the tail without popping.
     * Special purpose method for TransformerImpl, pushElemTemplateElement.
     * Performance critical.
     *
     * @return Node one away from the tail
     */
    public final Node peepTailSub1() {
        return m_map[m_firstFree - 2];
    }

    /**
     * Inserts the specified node in this vector at the specified index.
     * Each component in this vector with an index greater or equal to
     * the specified index is shifted upward to have an index one greater
     * than the value it had previously.
     *
     * @param value Node to insert
     * @param at    Position where to insert
     */
    public void insertElementAt(Node value, int at) {
        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if (null == m_map) {
            m_map = new Node[m_blocksize];
            m_mapSize = m_blocksize;
        } else if ((m_firstFree + 1) >= m_mapSize) {
            m_mapSize += m_blocksize;

            Node newMap[] = new Node[m_mapSize];

            System.arraycopy(m_map, 0, newMap, 0, m_firstFree + 1);

            m_map = newMap;
        }

        if (at <= (m_firstFree - 1)) {
            System.arraycopy(m_map, at, m_map, at + 1, m_firstFree - at);
        }

        m_map[at] = value;

        m_firstFree++;
    }

    /**
     * Append the nodes to the list.
     *
     * @param nodes NodeVector to append to this list
     */
    public void appendNodes(NodeSet nodes) {

        int nNodes = nodes.size();

        if (null == m_map) {
            m_mapSize = nNodes + m_blocksize;
            m_map = new Node[m_mapSize];
        } else if ((m_firstFree + nNodes) >= m_mapSize) {
            m_mapSize += (nNodes + m_blocksize);

            Node newMap[] = new Node[m_mapSize];

            System.arraycopy(m_map, 0, newMap, 0, m_firstFree + nNodes);

            m_map = newMap;
        }

        System.arraycopy(nodes.m_map, 0, m_map, m_firstFree, nNodes);

        m_firstFree += nNodes;
    }

    /**
     * Inserts the specified node in this vector at the specified index.
     * Each component in this vector with an index greater or equal to
     * the specified index is shifted upward to have an index one greater
     * than the value it had previously.
     */
    public void removeAllElements() {

        if (null == m_map)
            return;

        for (int i = 0; i < m_firstFree; i++) {
            m_map[i] = null;
        }

        m_firstFree = 0;
    }

    /**
     * Removes the first occurrence of the argument from this vector.
     * If the object is found in this vector, each component in the vector
     * with an index greater or equal to the object's index is shifted
     * downward to have an index one smaller than the value it had
     * previously.
     *
     * @param s Node to remove from the list
     * @return True if the node was successfully removed
     */
    public boolean removeElement(Node s) {
        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if (null == m_map)
            return false;

        for (int i = 0; i < m_firstFree; i++) {
            Node node = m_map[i];

            if ((null != node) && node.equals(s)) {
                if (i < m_firstFree - 1)
                    System.arraycopy(m_map, i + 1, m_map, i, m_firstFree - i - 1);

                m_firstFree--;
                m_map[m_firstFree] = null;

                return true;
            }
        }

        return false;
    }

    /**
     * Deletes the component at the specified index. Each component in
     * this vector with an index greater or equal to the specified
     * index is shifted downward to have an index one smaller than
     * the value it had previously.
     *
     * @param i Index of node to remove
     */
    public void removeElementAt(int i) {

        if (null == m_map)
            return;

        if (i >= m_firstFree)
            throw new ArrayIndexOutOfBoundsException(i + " >= " + m_firstFree);
        else if (i < 0)
            throw new ArrayIndexOutOfBoundsException(i);

        if (i < m_firstFree - 1)
            System.arraycopy(m_map, i + 1, m_map, i, m_firstFree - i - 1);

        m_firstFree--;
        m_map[m_firstFree] = null;
    }

    /**
     * Sets the component at the specified index of this vector to be the
     * specified object. The previous component at that position is discarded.
     * <p>
     * The index must be a value greater than or equal to 0 and less
     * than the current size of the vector.
     *
     * @param node  Node to set
     * @param index Index of where to set the node
     */
    public void setElementAt(Node node, int index) {
        if (!m_mutable)
            throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_NODESET_NOT_MUTABLE, null)); //"This NodeSet is not mutable!");

        if (null == m_map) {
            m_map = new Node[m_blocksize];
            m_mapSize = m_blocksize;
        }

        m_map[index] = node;
    }

    /**
     * Get the nth element.
     *
     * @param i Index of node to get
     * @return Node at specified index
     */
    public Node elementAt(int i) {

        if (null == m_map)
            return null;

        return m_map[i];
    }

    /**
     * Tell if the table contains the given node.
     *
     * @param s Node to look for
     * @return True if the given node was found.
     */
    public boolean contains(Node s) {
        runTo(-1);

        if (null == m_map)
            return false;

        for (int i = 0; i < m_firstFree; i++) {
            Node node = m_map[i];

            if ((null != node) && node.equals(s))
                return true;
        }

        return false;
    }

    /**
     * Searches for the first occurence of the given argument,
     * beginning the search at index, and testing for equality
     * using the equals method.
     *
     * @param elem  Node to look for
     * @param index Index of where to start the search
     * @return the index of the first occurrence of the object
     * argument in this vector at position index or later in the
     * vector; returns -1 if the object is not found.
     */
    public int indexOf(Node elem, int index) {
        runTo(-1);

        if (null == m_map)
            return -1;

        for (int i = index; i < m_firstFree; i++) {
            Node node = m_map[i];

            if ((null != node) && node.equals(elem))
                return i;
        }

        return -1;
    }

    /**
     * Searches for the first occurence of the given argument,
     * beginning the search at index, and testing for equality
     * using the equals method.
     *
     * @param elem Node to look for
     * @return the index of the first occurrence of the object
     * argument in this vector at position index or later in the
     * vector; returns -1 if the object is not found.
     */
    public int indexOf(Node elem) {
        runTo(-1);

        if (null == m_map)
            return -1;

        for (int i = 0; i < m_firstFree; i++) {
            Node node = m_map[i];

            if ((null != node) && node.equals(elem))
                return i;
        }

        return -1;
    }

}
